1. Field of the Invention
The invention is directed generally to a gas laser, and more particularly to a radio-frequency, diffusion-cooled stripline laser having two metal electrodes provided with means for cooling and with means for mutual fixing of the electrodes so that a discharge gap is formed between them, having an unstable resonator whose first resonator mirror is firmly connected to the base electrode, having a housing including a first and second end plate and an outside wall connected thereto vacuum-tight, the base electrode being firmly connected to the first face plate, and having at least two spacer rods.
2. Description of the Related Art
A stripline laser of the type described above is disclosed by European Published Application 0 477 865.
Until a few years ago, insurmountable difficulties opposed the design of compact, CO.sub.2 high-performance lasers. Due to the physical processes in the laser excitation, the efficiency of the lasers is highly dependent on the temperature of the gas not becoming excessively high, i.e., on an effective elimination of excess heat from the laser gas during its operation. It has been shown in diffusion-cooled CO.sub.2, lasers, wherein the heat is carried away by a stationery thermal conduction process from the hottest location in the center of the laser plasma to the cooled walls of the discharge vessel, that the output laser power is only dependent on the length and not on the diameter of the discharge. As a result, complicated convolution concepts were developed, on the one hand, to retain the compact dimensions of the laser despite powers into the kW range. On the other hand, quickly flooded, i.e., convection-cooled, lasers were developed. Quickly flooded lasers in the power category 500 through more than 10,000 Watts are currently commercially available. These lasers, which are not constructed for sealed-off operation, however, are bulky, have a high power-associated weight, and are dependent on a costly external gas supply and on pumping for fast gas circulation.
For these reasons, the only compact, diffusion-cooled CO.sub.2 lasers available have been lasers of the type referred to as waveguide lasers that have powers up to 200 Watts.
The fundamental principles of a stripline laser are disclosed in European Published Application 0 305 893 in which the discharge space thereof is not of a quadratic cross-section, by contrast to waveguide lasers, but instead is shaped on planar waveguide structures that are open toward the side. The combination of such a quasi-one-dimensional waveguide with an unstable resonator in the orthogonal direction thereby results in a diffraction-limited fundamental mode laser emission. In the stripline laser, heat is absorbed over a large area by closely adjacent electrodes, from which the heat is eliminated with the assistance of suitable coolants. It is, therefore, not necessary to pump the laser gas itself through the discharge space with a special cooling circulation means.
The article by R. Nowack et al., "Diffusionsgekiihlte CO.sub.2 Hochleistungs-laser in Kompaktbauweise" in "Laser und Optoelektronik", 23 (3)/1991, sets out the state of the art in stripline laser technology. Up to now, considerable difficulties have opposed the conversion of the above-described stripline laser concept into a practical design. The selection of a suitable electrode material and assuring the mechanical stability of the resonator structure vis-a-vis thermal stresses has proved to be especially problematical. For resolving the former problem area, a copending U.S. application filed simultaneously herewith and corresponding to European Patent Application No. 92114862.3 bearing the title "Stripline Laser with Compound Electrodes" is referenced and is herewith incorporated into the present disclosure.